Dryers, hair dryers in particular, are generally equipped with a fan or a turbine acting as blower. Often, the turbine is the centrifugal type, producing an airflow piped by walls of a casing of the dryer, to a nozzle concentrating the airflow to obtain effective pressure for drying. The drying function is generally improved by the presence of resistance downstream of the fan or turbine, so as to heat the expelled air. The entry of air at the level of the turbine is generally provided by a grille preventing access to the revolving parts of the turbine and protecting the appliance from fouling. This grille often comprises a first part fixed to the air admission bell of the centrifugal turbine and constituted by ribs (or beads) spaced such that they at least prevent penetration by a child's finger and a second part constituted by a filter made of a grille and/or by open-weave foam and whereof the frame is of such a size that it can screen out dust and hair. Often, this filter is made detachable by various solutions such as being inserted into a cover allowing it to be disassembled and reassembled quickly for easy cleaning.
A problem with drying appliances relates to the often high sound level of the motor and of the fan or the turbine. Indeed, the rotations of the motor and of the fan or of the turbine are sources of noise. The noise generated by such appliances is a function of the power of the motor and of the rotation speed of the turbine. This noise is particularly annoying for the user, especially in the case of hair dryers used close to the ears of users.
Solutions for optimising the yield of the centrifugal turbine and attenuating its sound level are known from the prior art. Certain solutions consist in decreasing the air turbulence generated near the blades by radiating the edge of the admission of the air upstream or downstream of the grille and of the dust filter. Certain solutions of the prior art consist of fitting the hair dryer with screens designed to diminish propagation of sound waves radiating perpendicularly to the air admission. Certain screens are made from insulating material and others are in the form of either a casing pierced with lateral air intake inlets, or a cover enclosing the body of the appliance at the level of the turbine such that this air admission occurs annularly between this body and this cover. The drawback to these solutions is that they are unsatisfactory. In fact, to mask the sound effect of the turbulence generated at the leading edge of the blades of the turbine, the flowing section of the air admission must be decreased to the maximum, to the detriment of the airflow yield of the turbine. Attaining the objective of flow is possible only by increasing the speed of the motor, inducing a decrease in the shelf life of the appliance. Also, the sound attenuation gained is then partly lost by the increase in noise generated by the motor. On the other hand, the lateral air intake inlets do not satisfactorily dampen the noise.
Another problem in the field of drying appliances relates to the fact that noise attenuation cannot generally be added to devices already distributed.